Injection molding machines are expensive to purchase, require expensive factory space and substantial quantities of electrical power. Additionally, set-up and operation of injection molding machines is a highly subjective trade, wherein there are significant set-up charges each time a tool is set. Starts and stops of such machines can be very expensive and there are always technicians and/or operators directly involved in such activities. The general practice on start up of an injection molding machine is provide an initial machine configuration (e.g., screw rotation rate, operable screw barrel temperature, injection pressure, etc.), then a “purging” process is performed where an operator first confirms that the injection molding machine is not connected to a mold, and then commences to process plastic but discarding the resulting plastic melt until the operator judges that the output plastic looks hot enough and appears to be of a low enough viscosity to commence molding test parts. Subsequently, a plurality of test parts are produced for inspection and/or analysis to thereby determine whether the machine is configured appropriately to successfully produce parts having the intended characteristics (e.g., fully conforming to the intended part shape, density, elasticity, etc.). Accordingly, the machine settings are generally fixed for mass producing the part.
The above described injection molding practice has substantial problems in that various part affecting parameters can change during the part mass production. For example, the operator settings may not be adequate for keeping the injection machine in a state for maintaining part consistency. In particular, it may not be possible to adequately determine whether the plastic is sufficiently uniformly heated so that acceptable parts can be produced therefrom. Additionally, since patches of plastic raw material inherently vary in their composition, variation in part production may be necessary dependent upon variation in the plastic raw material. Furthermore, the various injection molding parameters (whether settable by an operator or not) are generally interrelated with respect to producing acceptable parts. For instance, (a) nozzle injection pressure and plastic flow rate are inversely related, (b) plastic flow rate and plastic temperature are generally directly related, and (c) changes in screw rotation may generally be directly related to plastic temperature, although such may depend on the degree to which plastic heating is performed by shearing of the plastic in the screw barrel. Accordingly, it is very difficult to effectively and consistently configure a conventional injection molding machine to produce acceptable quality parts, and for very small quantities of parts the overhead for configuring such a machine can unacceptably expensive.
Accordingly, it would be advantageous to have an injection molding system and method of operation that is substantially more cost effective to manufacture and operate. Additionally, it is desirable for such a system and method to be less dependent upon operator trial and error to configure such systems for consistently producing acceptable quality parts.